Re: Raw Image to Bmp Image - C# Discussion Boards

3-Mar-04 5:44

I have un array of byte[] below:

<br />
byte[] img = new byte[78000]<br />
...<br />
Recept raw data from a fingerprint scanner<br />
...<br />

This array contains the data of a image with 300 of height and 260 of width (total = 300 x 260 = 78000).
Each position in the array (byte = 256) is a pixel (256 shades of gray).
How I create the Image object with this data?

Thanks for all response,
Laugh | :laugh:

Alexsander "Axia" Antunes

Mazdak3-Mar-04 5:54

Mazdak

3-Mar-04 5:54

You can write this to MemoryStream with WriteByte method then pass it in a cunstructor of Bitmap class or use Image.FromStream method.

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

Heath Stewart3-Mar-04 6:10

3-Mar-04 6:10

This actually wouldn't work. A Bitmap (as do all images) contain header information. This raw data does not. This is a similar situation with digital cameras and digital SLRs that can save RAW image data. They need to have a program that translates the RAW data into an image.

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Alexsander Antunes3-Mar-04 6:25

3-Mar-04 6:25

Where I have information about header of BMP images?
Thanks for all help! Smile | :)

Alexsander "Axia" Antunes

Mazdak3-Mar-04 6:27

Mazdak

3-Mar-04 6:27

Heath Stewart wrote:
A Bitmap (as do all images) contain header information

Well, what about if he writes them in that stream too?

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

Heath Stewart3-Mar-04 6:36

3-Mar-04 6:36

It would be possible to create all the information and serialize that (not .NET serialization, mind you) that to a stream, but it is incredibly error-prone and pain in the butt. For an app I wrote I did something similar that extracts icons and I have to serialize these correctly using the chain of sturctures required. Believe me, you don't want to do that!

As you saw in my other answer, .NET does provide a way to do this. You could always P/Invoke native APIs like CreateDIBitmap to accomplish this as well. These basically take minimal information and create and serialize the structures for your. I was about to answer that way when I found that you can't (easily) get a Bitmap from a handle WTF | :WTF:

and noticed the other constructor I've never cared to find before (that basically does the same thing I was going to mention with native APIs).

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Heath Stewart3-Mar-04 6:26

3-Mar-04 6:26

The Bitmap class and related classes and structs actually support this. You can use the constructor Bitmap(int, int, int, PixelFormat, IntPtr) to create a bitmap of a known size, source format, and the address of the first element in the data buffer. Basically, it uses similar functionality from GDI like the CreateDIBitmap API (although internally it uses GDI+ APIs).

This is untested, but should give you some idea

byte[] img = new byte[7800];
// Fill img
GCHandle gch = GCHandle.Alloc(img);
Bitmap bmp = new Bitmap(300, 260, 2400, PixelFormat.Format25bppRgb,
  gch.AddrOfPinnedObject());
gch.Free();

I don't currently have any raw data to try it out on, but this seems to be the way that is similar to how it's done in good ol' C/C++.

Let me know if it works. My digital camera outputs RAW images and eventually I was going to write a new front end since the one that came with it sucks.

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Mazdak3-Mar-04 6:29

Mazdak

3-Mar-04 6:29

Ok, I got the answer. Smile | :)

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

Alexsander Antunes3-Mar-04 8:21

3-Mar-04 8:21

In the code below:
Bitmap bmp = new Bitmap(300, 260, 2400, PixelFormat.Format24bppRgb, gch.AddrOfPinnedObject());

What is the third parameter (2400)? In th VS Documentation is the stride parameter, what is this?

Thanks for all,
Smile | :)

Alexsander "Axia" Antunes

Heath Stewart3-Mar-04 8:36

3-Mar-04 8:36

It's the number of bites in a single row. Since your image is 300 pixels wide and you're dealing with a byte[], which should actually be 300 to represent 300 bytes. I was multiplying by 8 to get the number of bits, which is incorrect (not sure what I was thinking).

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Alexsander Antunes3-Mar-04 8:51

3-Mar-04 8:51

My image is 300 of heigth and 260 of width.
How value is for stride? 2080(260 * 8 bits) or 2400 (300 * 8 bits)
Smile | :)

Alexsander "Axia" Antunes

Heath Stewart3-Mar-04 8:57

3-Mar-04 8:57

No, like I said - I made a mistake. Just use 260 for the value, and swap 260 and 300 for the first two params since I accidentally reversed your width and height.

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Alexsander Antunes3-Mar-04 8:54

3-Mar-04 8:54

My image is 300 of heigth and 260 of width.
How value is for stride? 2080(260 * 8 bits) or 2400 (300 * 8 bits)
Smile | :)

But in 2 cases I have the following error:
Additional information: Identification is not fixed.

Alexsander "Axia" Antunes

Heath Stewart3-Mar-04 8:58

How to draw on nonclient area of a form ?

3-Mar-04 8:58

One what like do you get this? Debug your application and find out exactly where the error is happening.

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Andres Coder3-Mar-04 5:11

3-Mar-04 5:11

How can I draw on a nonclient area of a form ? I mean the border and the caption. Before I started using C#, I just used WM_NCPAINT message to do the job, but I have no ideas how to do it in C# now ? Can anyone help me ?

Also, how can I get the size of the nonclient area ?

Regards, Desmond

Andres Coder3-Mar-04 5:30

3-Mar-04 5:30

Maybe I somehow have to import a some procedure form Win32 API, using DLLImport attribute ?

Heath Stewart3-Mar-04 6:09

3-Mar-04 6:09

Override WndProc and continue to use WM_NCPAINT. In your handler, you can get a Graphics from several means, such as Graphics.FromHwnd, passing the HWND (an IntPtr) that you get along with the Message that you're handling in WndProc.

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Andres Coder3-Mar-04 7:01

3-Mar-04 7:01

Thanks, but it's a bit hard for me to understand this. Could you please support me with a basic code example ?

Heath Stewart3-Mar-04 8:40

3-Mar-04 8:40

You do just like you did in C++, only using managed code. If you need examples, try http://www.google.com[^]. There's many examples out there I've seen in the past.

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Andres Coder3-Mar-04 8:44

Connecting to MySQL with ODBC

3-Mar-04 8:44

Did so -> problem solved. Thanks. Note that I actually didn't came from C++, but from Borland Delphi (it's not that bad, really).

sps-itsec463-Mar-04 3:12

sps-itsec46

3-Mar-04 3:12

Hi guys,

I think it's a simple question: I connect to a MySQL database with OdbcDataAdapter and besides the data I want to get the schema of the database directly from the database, so I use something like this:

public DataSet GetData()
{
    // Create DataSet
    DataSet ds = new DataSet(datasetName);
    OdbcDataAdapter adapter = new OdbcDataAdapter();
    adapter.SelectCommand = GetSelectAllCmd();  // Generates Query: "SELECT * FROM " + tableName
 
    // Get schema from database
    adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
 
    // Rename table
    adapter.TableMappings.Add("Table", tableName);
 
    // Get data
    adapter.Fill(ds);
 
    // Do we have errors?
    if(ds.HasErrors)
        ds.RejectChanges();
    else
        ds.AcceptChanges();
 
    // Free resources
    adapter.Dispose();
 
    return ds;
}

Everything seems working fine, but the schema isn't transfered correctly. The MaxLength property of the DataColumn member has the value of the longest entry in the database. For example if there is a column called 'name' and the database has an entry like 'John' the MaxLength property is 4. But I specified the 'name' column to allow 100 chars while creating the table (... name VARCHAR(100) NOT NULL, ...).

Furthermore I'm not able to change the MaxLength property. The following has no effect:

ds.Tables[tableName].Columns["name"].MaxLength = 100;

So I'm not able to insert a name to the 'name' column that is longer than 4. I get the error "The value violates the MaxLength limit of this column". Many thanks in advance!!!

Regards, mYkel

P.S.: Sorry I also posted this in SQL/ADO/ADO.NET forum but perhaps it fits better here...

Re: Connecting to MySQL with ODBC

Heath Stewart3-Mar-04 6:07